HUB CAPS & GASKETS

Hub Caps & Gaskets For Peterbilt Trucks

Hub caps seal the wheel end hub cavity on oil-lubricated axles, protecting bearings and gears from contamination while keeping gear oil contained. A leaking hub cap gasket is one of the most common wheel-end fluid loss sources on Class 8 trucks — and oil on brake linings from a hub leak is an immediate out-of-service condition. We carry hub caps, hub cap gaskets, sight glass assemblies, and fill plugs for common Peterbilt drive and trailer axle configurations.

Frequently asked questions about hub caps & gaskets

How do I know if my hub cap gasket is leaking?

Oil streaking down the wheel face, oil residue on the inside of the wheel, or a wet ring around the hub cap perimeter are the most visible signs of a leaking hub cap gasket. On a pre-trip inspection, the inner wheel face and hub area should always be checked for oil. Even a minor seep should be addressed — what starts as a gasket weep can progress to a full seal leak that contaminates the brake linings and creates a hazardous braking condition.

How often should hub cap gaskets be replaced on a Peterbilt?

Hub cap gaskets don't have a fixed replacement interval — they're typically replaced when the hub cap is removed for bearing service, oil level checks, or wheel end inspection. Cork and rubber gaskets compress and take a set over time, so a gasket that's been removed and reinstalled multiple times may not seal reliably and should be replaced with a new unit at each removal. Keeping a supply of the correct gaskets for your axle make on hand prevents a hub cap R&R from turning into a parts run.

What type of oil do I use to fill a hub on a Peterbilt drive axle?

Most Peterbilt drive axles use a gear oil specified by the axle manufacturer — Meritor axles typically call for SAE 75W-90 or 80W-140 gear lubricant meeting their specification. Some newer axles use synthetic gear oil for extended drain intervals. Always use the axle manufacturer's specified lubricant type and viscosity — mixing incompatible lubricants or using the wrong viscosity can cause premature bearing and gear wear. Check the axle nameplate or service manual for the correct specification for your specific axle.

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